Improvement in processes of preparing paper-pulp



UNITED STATES JOHN MAYRHOFER, OF NEW YORK, N. Y.

Specification forming part-of Letters Patent No. 25,976, dated November 1, 1859.

To all whom it may concern:

Be it known that I, JOHN MAYRHOFER, of the city, county, and State of New York," have invented a. new and useful Improvement in the Process of Preparing Paper-Pulp for Making Paper impervious to-Water; and I do hereby line solution nntil-the mixture becomes of about the consistency of molasses,taking care to stir the mixture while boiling, .I prefer to apply the required heat for. boilingthe mixture by' ste'arn,-as. the heatcan be readily checked when required,and-discoloration by bui'ning isprevcnted. I ascertain when the rosin is properly dissolved when. foam ceases to appear on the surface, or by diluting the mixture with warm water to see if it will present a milky appearance. For three hundred and twenty parts, by weight, of dry paper-pulp,-

I take seventy-five parts, by weight, of the alkaline solution of rosiudil-uted in not less than double the weight of warm water. This'dilntc solution is to be applied to the pulp in the stuff-engine, and the griruling of'the pulp is then to be continued for from'ten to fifteen minutes. Before applying the rosin solution care'shonld be taken to have the pulp free from alkali, as the presence of alkali other than that contained in; the solution 'will be injurious.

After the paper-pulp has been ground in-the' engine, as before stated, with the rosin solution, I add very gradual] y fifty parts, by weight, of what is known as concentrated English sulphuric acid, and continue the grinding while the acid is being added and for fifteen minutes after the whole quantity has been put in. The pulp thus prepared is then to be made into paper in the usual manner, and must be dried by .calenderingwith heated rollers, or by causing it to pass in contact with heated metallic surfaces, as this is essentialto produce the re quired effect.

Ifit be desired'to apply coloring-matter, care should be taken to use neutral colors,'as the presence of acid or alkalies in the coloring-matter will prevent the-production of the renuired result.

By means of this process-the minute fibers of the pulp are saturated with the alkaline solution, and when the acid is applied it will render the solution so incorporated with the fibers insoluble, and in consequence the paper is formed notofpnlp merely, but ot'pulp' and the insolublesubstance which pervades the fibers, and when heat is afterward applied to the sheets of paper to dry out the moisture the insoluble substance thus produced and the. --fibers so saturated will produce paper entirely impervious to water; I

When the paper to be thus produced is re quired to be coloredthe coloring-matter sho Id be applied to the pulp after the alkaline so ution and the acid have been thoroughly mixed, 1

Having thus described my-improved processand the ingredients employed, as also-the proportions which I have found to be best, -I am aware that sizing has been employed to produce paper, and that the sizing so applied has had the efl'ect of-reducing the absorbent property of the paper, and thisI do not claim.

What [do claim as my invention, and dc-=- sire to secure by Letters Patent in making paper impervious to water, is-- Mixing the alkaline solution of rosin. with the pulp, and then adding what is known as English sulphuric acid, and after the sheets have been formed drying them by contact with heated metallic surfaces, all'substan tial'ly as and for the purpose specified.

JOHN MAYRHOFEE Wi triesses ANDREWDE-IQA'GY, T. P. HANDY, 

